Hi all,

We have encountered a challenge while using mbedTLS 3.5.1 and would greatly appreciate the assistance of the experts. Thank you in advance for your support.

I used mbedTLS 3.5.1 to connect to the server acc.connect.cpms.milence.com, and the TLS handshake failed with an Alert (Level: Fatal, Description: Protocol Version) error. Detailed information is described at this GitHub issue.

• We attempted to connect with the Windows EDGE browser and found through packet capture that the handshake was successful.
• We were also able to successfully handshake using TLS 1.2.
• When we limited the supported group to only: MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1 and used TLS 1.3, the handshake was also successful.

For more details, please refer to the discussion on GitHub: Handshake fail with "Alert (Level: Fatal, Description: Protocol Version)" · Issue #10141 · Mbed-TLS/mbedtls.

Best Regards,
Fu Baicheng